1. Field of the Invention
The present invention relates to an apparatus for use in semiconductor processing, more particularly to an alignment aid for an electrode plate assembly utilized in the film etching process.
2. Description of Related Art
Wet and dry etching are currently the most common techniques used in semiconductor processing. The dry etching technique utilizes a plasma to perform film etching, as compared to the wet etching technique which uses a solution to carry out the etching. One of the major benefits of dry etching is that it can perform what is termed "anisotropic etching." Based upon the particles generated by plasma, the etching rate in a vertical direction is much greater and more accurate than in a horizontal direction. When a voltage is applied to accelerate charged ions of the generated plasma, ion bombardment takes place which results in film etching. This technique, which utilizes momentum transfer to perform the etching, is termed "sputtering etch."
A second type of dry etching is know as "plasma etching." Plasma etching uses plasma to decompose reactive gas molecules into ions which react on the film being etched. The chemical reaction of the reactive ions produces the intended etching. Like the above mentioned wet etching, this type of dry etching relies upon a chemical reaction and therefore provides greater selectivity but less anisotropy. In order to realize a dry etching technique with greater selectivity and higher anisotropy, reactive ion etch (RIE) has been developed and has become a popular technique in semiconductor etching.
The above mentioned dry etching techniques use a plasma generator to create the plasma necessary to perform the intended etching. Plasma contains gas molecules in a breakdown state and functions as a conductor for transferring currents. The generation of plasma is completed by applying voltage through a top electrode plate and a bottom electrode plate.
A portion of a conventional electrode plate for installation to an etching console is shown in FIG. 1. The electrode plate includes a cooling electrode plate 10, a covering plate 120 and a plurality of screws (not shown).
The cooling electrode plate 110 is a substantially disk-shaped metallic plate having a plurality of screw holes 114, and a plurality of vent holes 116. The covering plate 120 is a thin, substantially disk-shaped plate also having a plurality of screw holes 124 and a plurality of vent holes 126. The vent holes of the plates 110, 120 may be round in shape, for example. Each of the vent holes 116 of the cooling plate correspond in size and position with the vent holes 126 of the cover plate. When the cooling electrode plate 110 and the covering plate 120 are coupled correctly, the vent holes 116 of the cooling plate will align and communicate with the vent holes 126 of the cover plate.
The installation of the electrode plate requires aligning the screw holes 114 of the cooling electrode plate with the screw holes of the covering plate 120 and then screwing the plates together to an etching console (not shown).
Since the above method of installation does not assure alignment of the vent holes, misalignment of the vent holes can occur and result in abnormal etching or expensive delays in the manufacturing process.